1. Field of the Invention
The invention pertains generally to sensors such as frequency sensors, motion sensors, position sensors and other similar sensors and in particular to noise discrimination circuits for use with said sensors, that is, circuits which are immune from the noise frequently caused by spurious short duration pulses. The elimination of the effects of high energy electromagnetic noise of very short duration with high amplitude is achieved in a frequency sensor.
2. Description of the Prior Art
Pickup circuits for use with various static and dynamic sensors initially receive a noise modulated signal from the sensor device. Prior art pickup circuits then usually filter the noise modulated signal before further processing, using a low pass filter. However these filtered signals are still both voltage dependent and amplitude dependent. Spurious high frequency pulses with high amplitude and of short duration can pass through such a filter. The present invention is directed to a circuit which minimizes the shortcomings of the low pass filter and thereby discriminates the true signal from noise more effectively than heretofore achieved.